# CVE-2026-53636: Open edX LTI OAuth Replay Attack

> Attackers can replay captured LTI launch requests indefinitely due to missing nonce and timestamp validation in the Open edX LMS platform.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 2 Sep 2026
- **Updated:** 2 Sep 2026
- **Also known as:** GHSA-6gm5-c49g-p3h9

## What is CVE-2026-53636?

CVE-2026-53636 is a medium-severity vulnerability in openedx-platform, published on 2 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Open edX Platform enables the authoring and delivery of online learning at any scale. Prior to commit 3a5ac85, a security vulnerability has been identified in the Open edX LMS platform's LTI (Learning Tools Interoperability) Provider implementation. The validate_timestamp_and_nonce function in lms/djangoapps/lti_provider/signature_validator.py does not validate OAuth nonces or timestamps, allowing an attacker who captures a valid LTI launch request to replay it an unlimited number of times without detection. This issue has been patched via commit 3a5ac85.

Weakness: CWE-294 (Authentication Bypass by Capture-replay)

## Which versions are affected by CVE-2026-53636?


## How do I fix CVE-2026-53636?

No fix has been published for CVE-2026-53636 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-53636 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53636 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53636 and fix it if it is affected.

What it is: CVE-2026-53636 is a medium-severity vulnerability in openedx-platform, published on 2 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53636 exists.

Affected product: openedx-platform. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53636/ (Markdown: https://insights.sbomify.com/CVE-2026-53636/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53636
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53636
- OSV: https://osv.dev/vulnerability/CVE-2026-53636

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53636/
Summaries are generated and may contain mistakes; the official description above is the record.